Ballastless track structures, which are featured with high regularity, high stability, high durability and high reliability, are accepted by high-speed railways in countries all over the world and also broadly applied to high-speed railways in China. At present, there are numerous types of ballastless track structures at home and abroad, generally including two structural systems, a unit one and a longitudinally continuous one.
Comparing and analyzing technical characteristics of different types of ballastless tracks, a unit ballastless track mainly includes structural layers including a track slab, a poured-field layer, and a base etc. The track slab applies a prefabricated slab. The poured-field layer and the base are arranged laid below the track slab in turn, wherein as a key structural layer for elasticity adjustment and force transmission support of the ballastless track structure, the poured-field layer directly affects rapid and safe operation of a high-speed train. In an existing ballastless track structure, a track slab is longitudinally laid on a poured-field layer along a line and a circular convex barricade is applied between two adjacent track slabs along the longitudinal direction during a laying process. After the track slab is adjusted and installed in place, an asphalt mortar poured-field layer is filled between the track slab and the poured-field layer, and resin mortar is filled in a gap between the track slab and the circular convex barricade. The track slab is provided as a unit having a structure with explicit force bearing and transmission as well as good maintainability. However, a disadvantage is the tedious construction of the convex barricade. In addition, after the line is put into operation for a period of time, the track slab may be split from the asphalt mortar poured-field layer and a longitudinal end of the track slab may warp easily, which undoubtedly causes adverse impact on train stability and riding quality, and track system durability.
A longitudinally connected ballastless track slab applies prefabricated polished slabs with pre-split cracks. The slabs are longitudinally connected, and the track is laid with relatively high precision. However, the longitudinally connected ballastless track slab, which is complicated in connection structure, has bad environmental adaptability and maintainability. A double-block ballastless track structure with relatively simple components and poured-in-place roadbed slabs is highly adaptable to different types of fasteners and relatively low in construction cost, but with a large amount of concrete construction and hardly-controlled roadbed slab cracks.
Valuable experiences in aspects including structural design, construction methods, technical requirements of track foundations etc. of ballastless tracks has been accumulated during the pass more than 50 years of researches and practice in China, which lays a foundation for further development of ballastless track technologies.